I don't have computer . Can I create a course using smartphone?
Sure u can.
It's possible to record the videos and audio for your course using a smartphone, but you may need to purchase a lavalier mic or something in order to get acceptable audio quality.My concern is how you'll edit the videos, store them, and upload them to Udemy without a computer. I would think that would be extraordinarily difficult.
Maybe you can try, but it will be difficult. And also the resolution quality won't be good from all the perspective